At first , connect Cubietruck by USB ,and open terminal:

  $adb shell

So you will input the Android-Shell Command-Line,and see where the system file mounted:

  $mount

You can see the block /dev/block/system mount on /system,

then you connect SATA with Cubietruck,and see what block is the SATA:

  $ls /sys/devices/platform/sw_ahci.0/ata1/host0/target0:0:0/0:0:0:0/block

You will see the SATA block(maybe it's sdb, sdc or sdd,but it's no problem):

Now you know the block,use this command:

  $dd if=/dev/block/system of=/dev/block/sda(Your SATA block)

Just wait for about 1 minutes,it will success:

After you copy the system file to SATA,you should modify SDK:

  $cd V2.0_A20/android/devices/softwinner/sugar-cubietruck/ && ls
  $vim init.sun7i.rc

And "mount ext4 /dev/block/system" changes to "mount ext4 /dev/block/sda",like that:

Save and quit,complie the android image.If you don't konw how to complie,refer to here

After compile success,do this:

• Install the new image to Cubietruck.

• Connect the SATA first( must first! If you don't do this it wouldn't boot)

• Charge it with electricity,you will see it Boot from SATA.